[TowerTalk] Soldering Radials?

[F5vjc]

I'm soon about to improve my HF2V radial field connection point.

I have a copper tubing ring which I will use and I intend to solder
the radials to this.

I know the standard 60 /40 rosin cored solder is not suitable for long
term outdoor soldered connections.

What is the recommended solder and flux to use for outdoor soldered connections?
I expect I will need to use a butane torch?

The radial ring will not be buried, and I don't want to seal the
soldered connections with some sort of sealant, so I can easily add
more radials as and when I can, 32 at the moment.

I'm totally familiar with light electronic circuit soldering but not
with this "Heavy Duty Outdoor stuff"

Thanks es 73, Deni
F5VJC